The product being produced is a particular copolymer where (NPCl.sub.2).sub.n has been reacted so that all but about 0.5% or less of the chlorine atoms have been replaced by a combination of phenoxy, alkylphenoxy and allylphenoxy. The allylphenoxy is included to furnish unsaturated groups to serve as cure sites in the resulting polymer for cross linking and vulcanization. The substantially complete replacement of the chlorine atoms is necessary for the product to be useful in certain fireproof foam formulations.
Conventionally, these copolymers with some substituents being allylphenoxy and substantially all the chlorine atoms replaced have been prepared in a two stage chlorine replacement process wherein the appropriate phenoxides were reacted with (NPCl.sub.2)n. In the first stage all the allylphenoxide and less than the stoichiometric amount of alkylphenoxide and unsubstituted phenoxide were reacted with (NPCl.sub.2).sub.n. In the second stage alkylphenoxide and unsubstituted phenoxide were used in excess to substantially replace the remaining chlorine atoms. The two stage reaction was utilized because it was thought that an excess of phenoxide was necessary to obtain substantial replacement of chlorine atoms and one stage was not desirably used with such an excess because alkylphenoxides and unsubstituted phenoxides react preferentially over allylphenoxide. The reaction was preferably carried out at 300.degree. F. for 14 hours (time of reaction of both stages) with the total cycle time being about 24 hours. The use of an excess of phenoxide necessarily resulted in the need to remove the excess after reaction, and the relatively long reaction time sometimes resulted in degraded product.
One stage chlorine replacement reactions have been utilized in producing substantially chlorine free copolymers but the reaction was carried out utilizing an excess of phenoxide reactants and a relatively long reaction time i.e. 24 hours at a 300.degree. F. temperature. See Cheng U.S. Pat. No. 4,116,785. Here again the use of excess phenoxide necessarily resulted in the need to remove the excess after reaction, and the relatively long reaction time could result in degraded product.
Dieck et al. U.S. Pat. No. 4,055,545 discloses making poly(aryoxyphosphazene) copolymer foams by reacting (NPCl.sub.2).sub.n with a mixture of phenoxides including unsaturated phenoxide, preferably using an excess of phenoxide reactants to assure complete reaction of all available chlorine atoms, at a temperature and length of time ranging from about 25.degree. C. for 7 days to about 200.degree. C. for 3 hours. Use of excess phenoxide as preferred requires removal of the excess after the reaction. Interpolation within the above range indicates a time of about 46 hours for a reaction temperature of 300.degree. F., assuming a linear relationship.
Even where elastomeric copolymers were being prepared (with larger amounts of residual chlorine than mentioned above) so that a less than stoichiometric amount of phenoxide reactants were used, reaction conditions of 300.degree. F. and 24 hours have been used (See Example 1 of Cheng et al. U.S. Pat. No. 4,179,555).